The Gallery of Natural Phenomena

The earth, the sea, the sky - and beyond

The Ancient Natural World Part 5

In A.D. 141, Halley's Comet returned. The comet swung around the Sun on March 22, and the Chinese observers first saw it on March 27, as a 'broom star' in the east with a pale blue tail about nine degrees long. The comet was visible until late April, when it disappeared in the constellation of Leo. It would return in A.D. 218.

Claudius Ptolemy, who died about A.D. 178, probably observed Halley's Comet, but if so he left no surviving record of it. He was interested in comets as tools of astrology. He described comets as 'occasional phenomena in the upper atmosphere', and casually classified their shapes as beams, trumpets, jars, 'and the like'. The importance of comets was what they portended for the inhabitants of the Earth.

Comets, according to Ptolemy, foretold “wars, hot weather, disturbed conditions, and the accompaniments of these; and they show, through the parts of the zodiac in which their heads appear and through the directions in which the shapes of their tails point, the regions upon which the misfortunes portend.” The length of time comets were visible indicated the duration of the event they foretold: “their appearance in the orient betokens rapidly approaching events and in the occident those that approach more slowly.”

This is all Ptolemy has to say on the subject of comets. On the basis of this he has been accused of ushering in 'more than sixteen centuries of cometary superstition', which seems rather unjust. Pliny believed that comets presaged disaster, and Seneca said that comets had a 'bad character'. Cometary superstition was already rife. Ptolemy, who became very influential in later centuries (he was called 'the divine Ptolemy' by Hephaestion of Thebes), merely made it philosophically respectable.

MALEFICENT PLANETS

To Ptolemy, astrology was not superstition but science. His work had made it was possible to predict the movements of the Sun, Moon, and planets, and now it should be also possible to predict 'the changes which they bring about in that which they surround', i.e., the Earth. Aristotle's divine fifth element, ether, surrounded and permeated all things, and the lesser elements, such as fire and water, were affected by the motions of the ether as the heavenly bodies moved through it.

That the heavenly bodies influenced events on the Earth could not be denied. The Sun brought heat and cold, drought and moisture, according to its movement, and the Moon controlled the tides. Therefore it was only reasonable to conclude that the other bodies of the sky must also affect the Earth. The effects of the Sun upon the Earth were obvious, 'comprehended by very ignorant men, nay, even by some animals'. The effects of the other heavenly bodies were more subtle, and could be discovered only by diligent observation.

However, Ptolemy attributed qualities to the planets which seem to depart more and more from the ideals of observation. It seemed possible that Saturn might have a cooling and drying quality, because of its distance from the Sun and the Earth, and that Mars might be hot and dry, owing to its fiery colour and nearness to the sphere of the Sun. Jupiter and Venus were temperate planets, while Mercury had a combination of qualities. Less evident to observation must be the statement that Venus and Jupiter were beneficent planets, while Saturn and Mars were maleficent.

The qualities of the fixed stars also had to be taken into account. For instance, Ptolemy says that “the stars in the head of Aries...have an effect like the power of Mars and Saturn mingled; those in the mouth like Mercury's power and moderately like Saturn's; those in the hind foot like those of Mars, and those in the tail like those of Venus.”

Then the positions of the stars had to be considered, then the positions of each planet with respect to a star which might temper or increase the planet's qualities according to the star's natures. Once the astrologer had accomplished that, he had to consider the nature and position of the constellation in which that star or planet might be found, then calculate how these combined influences might react with the powerful qualities of the Sun and Moon.

It soon becomes evident that predicting the effects of the heavenly bodies upon the Earth and the inhabitants thereof is a vast and complex undertaking, which rests upon some rather arbitrary assumptions about invisible universal forces. Even if the assumptions are taken for granted, and the qualities assigned to each heavenly body accepted as fact, the number of variables and the possibilities for miscalculating them seem to make the whole business no better than a guess. Ptolemy himself was cautious, saying that, “even though one approach astrology in the most inquiring and legitimate spirit possible, he may frequently err...because of the very nature of the thing and his own weakness in comparison with the magnitude of his profession.” He could not have foreseen, even with the aid of his science, the almost idolatrous awe with which the centuries to come would regard him, and how reluctant to admit the possibility of error future practitioners of astrology would be.

SUPERNOVA

GUEST STAR OF THE SOUTHERN GATEThe supernova of A.D. 185, as seen at sunrise from Lo-Yang, China (34° 50’ N., 112° 30’ E.), December 7

Only the indefatigable Chinese recorded the new star of A.D. 185. The astronomical treatise Hou-han-shu says that on December 7, a 'guest star' appeared in the constellation of Centaurus, hovering just above the horizon before dawn. “It was as large as half a mat, it showed the five colours, and it scintillated.” The new star slowly faded, and disappeared about A.D. 187.

The new star must have been very brilliant to be visible at such a low altitude. Had it appeared half a century earlier, Ptolemy might have seen it from Alexandria, and revised his views about the nature of the fixed stars. The astronomers of Lo-yang looked upon the star, the first supernova of history, and considered its nature as a sign in the sky.

Emperor Hsaio-ling, the penultimate ruler of the Later Han Dynasty, found that the new star was one of ill-omen. The year before the star, a rebellion had disturbed the northern provinces. The imperial astronomers were safe in issuing the standard prognostication for this type of portent, which was insurrection, and several thousand people were killed in various conflicts during the visibility of the star.

THE SUN RED AS BLOOD

New Zealand, one of the few places in the world human beings had not yet reached, was shaken by possibly the greatest volcanic catastrophe in history about A.D. 186. An eruption began beneath Lake Taupo in the North Island. Soon an ash cloud rose which dwarfed the one over Vesuvius in A.D. 79, billowing to a height of 50 kilometres (31 miles). Then the vent collapsed into the magma chamber, triggering an explosion of unprecedented magnitude.

A gigantic blast erupted upward and outward. Thirty cubic kilometres of hot ash, pumice, and rock flowed like a searing liquid over an area 160 kilometres across in just seven minutes. Mountains 1,500 kilometres high were engulfed, and a cloud of ash covered 30,000 square kilometres. Ash fell to a depth of a metre 50 kilometres from the volcano. 100 kilometres downwind it was still 25 centimetres (10 inches) deep. Vegetation was charred up to fifty miles away. A vast cloud of dust and sulphuric droplets was injected into the upper atmosphere and began its journey around the globe.

During the reign of the emperopr Ling Ti (A.D. 168 – 189), the Sun was dimmed in China. “Several times the Sun rose in the east as red as blood and lacking light”, and the imperial astronomers recorded 'a black vapour as large as a melon' upon its face in A.D. 188. In A.D. 189, the Hou-han-shu recorded that “the Sun was orange in colour and within it was a black vapour like a flying magpie.” The bright disc of the Sun was veiled, and naked-eye sunspots became visible.

The Romans, enduring the excesses of the emperor Commodus, recorded that during his reign (A.D. 180 – 192), “some stars shone continuously by day, others became elongated and seemed to hang in the middle of the sky”.

All this is open to dispute, of course. The Taupo eruption has an alternative date of A.D. 131, and the Chinese red skies may have been caused by an eruption in Alaska, or some non-volcanic cause such as low-level dust. The supernova of A.D. 185 has been suggested for the Roman observations, although it seems that it would have been scarcely visible at Rome. The account does say 'stars' and not 'a star'. Suggestions that the 'stars' were an auroral appearance should be treated sceptically, as the aurora has become an all-purpose explanation for any unusual sky event.

STARS, FIRES, AND SILVER RAIN

The Roman historian Dio Cassius became a witness to a sign in the sky in A.D. 193. The emperor Didius Julianus, who had purchased his position after the Praetorian Guard had offered it for sale in March of A.D. 193, was offering a sacrifice before the senate house. Three 'stars' appeared round the Sun. “These 'stars' were so very distinct that the soldiers kept...looking at them and pointing them out to one another, while declaring that some dreadful fate would befall the emperor. As for us...the fear of the moment would not permit us to gaze up at them save by furtive glances.”

Dio believed that the three 'stars' represented the governors of Britain, Pannonia and Syria, who were rivals for the imperial throne. The winner was the governor of Pannonia, Lucius Septimus Severus, who marched on Rome and had Julianus killed on June 1. Julianus had been emperor for 66 days.

What the 'stars' were is something of a mystery. The most obvious explanation is that there were two parhelia each side of the Sun and an upper contact arc above, but these would have looked more like 'suns' than 'stars'.

Severus' position was not secure until he had dealt with the governor of Syria, Pescennius Niger. The decisive battle took place at Issus in March or April, A.D. 194. Dio says that Niger was winning when a thunderstorm advanced over Severus' legions and unleashed a fury of rain, wind and hail directly into the faces of Niger's men. “This did not trouble Severus' troops, as it was at their backs...Most of all, this opportune coming of the storm inspired courage in the one side, which believed it was being aided by Heaven, and fear in the other.” Niger's force fled with the loss of 20,000 men.

Severus had one more rival 'star' to deal with, the Governor of Britain, Clodius Albinus. According to Dio, 'the entire world was disturbed' by the civil war, and apprehensions were increased when the nocturnal sky blazed with auroral light. The 'sudden appearance of such a great fire in the northern sky at night' led some people to suppose that 'the whole city was burning, and others that the very sky was afire'.

BOTHYNIAn auroral display with beams radiating from a clear circle (the ‘dark segment’)

Over a hundred years before, Seneca, following Aristotle, had sought to classify the aurora. He said there were three types; bothyni, when 'within a surrounding corona there is a great gap in the sky like a hole dug in a circle', pithiai, a round mass of light 'like a barrel (which) either darts by or blazes in one place', and chasmata, when 'a gap in the sky sends out flame'. Seneca described the red, white, and yellow colours of the aurora, how it sometimes flickered with outbursts and rays, and sought to explain it.

Aurorae, he said, were fires started by friction of the air and driven violently by a wind. The colour of the fire depended on what type of element had burst into flame, and the flickering occurred as each burning element sought out its own type of fuel. Even in Seneca's time, aurorae were the 'cause of terror' to mankind. Now observation was fading, but terror remained.

Dio found another phenomenon at the time even more astonishing. A 'fine rain resembling silver' descended from a clear sky upon the Forum of Augustus. Dio did not see the silver rain falling, but noticed it afterwards. He plated some bronze coins with the 'rain', but it had disappeared after four days.

Serverus defeated Albinus on February 19, A.D. 197, and returned to Rome for a few months of relative peace. The Scythians had been contemplating trouble in A.D. 197, but during a council of war their three chiefs were killed by lightning, which restrained them.

A HUGE FIRE BLAZED UP

One of the earliest accounts of an eccentric natural event that has baffled and exasperated people for at least 2,000 years comes from the Greek historian Athenaeus, who says there was a rain of frogs in Sardinia. Frogs dropped from the skies in such large numbers that people were unable to walk without stepping on one. The frogs were presumably cleared (or hopped) away, and the incident became a nine days' wonder. Various suggestions as to where the frogs came from were no doubt offered, and all were found unsatisfactory.

Mount Vesuvius had been restless ever since A.D. 79. Now a plume of smoke by day and a glow by night gave notice that its centuries of uneasy sleep were over. About A.D. 172, Galenus reported, 'the matter in (Vesuvius) is still burning'. In A.D. 202, Dio says, 'a huge fire blazed up' on the volcano, “and there were bellowings mighty enough to be heard in Capua...In view, now, of what happened on Vesuvius, it seemed probable that some change in the State was about to occur”. However, the only change he could point to was the failure of an attempt a few years later to assassinate Severus.

Macrinus became emperor of Rome on April 11, A.D. 217. Dio says he 'was not destined to live long', as a disastrous portent soon afterwards showed. On August 23, during a thunderstorm with torrential rain, lightning struck the Colosseum. The conflagration that followed was unstoppable, despite the rain, and the building was ruined. On the same day, a great flood of the Tiber invaded the Forum and swept people away. The Colosseum was repaired in a leisurely fashion and was not restored until A.D. 238.

Halley's Comet returned in A.D. 218, and swung round the Sun on April 6. The Chinese astronomers saw it in the morning for about twenty days, then it passed into the evening sky and was pointed and bright. Dio says that a “star, whose tail extended from the west to the east for several nights, caused us terrible alarm”. (Dio actually says there were two comets. “The comet was seen for a considerable period; also another star, whose tail extended...” Possibly he thought Halley's morning appearance was a separate comet).The emperor Macrinus' death, in June A.D. 218, was 'naturally blamed on the comet', according to some, although he was in fact assassinated by a centurion. The comet would return in A.D. 295.

A TERRIBLE BLOODY SWORD

The third century A.D. was a period of fierce winters and eerie portents in Britain, if we are to believe Dr. Short and John Seller, who were both reluctant to divulge their sources, if any. Hail 'bigger than duck's eggs' fell in A.D. 207, and in A.D. 264 hailstones fell weighing over a pound. In the year A.D. 220, there was a frost in Britain lasting five months. This followed the winter of A.D. 134, when the Thames was frozen for two months, and the three-month frost of A.D. 173, when deep snow lay for 13 weeks and was followed by famine. All these winters are on the authority of Dr. Short, who is the first to mention them. C. E. Britton, while compiling A Meteorological Chronology to A.D. 1450, asked the readers of the Royal Meteorological Society journal if they knew of any earlier reference to these severe winters. He received no reply.

John Seller, in his 1696 History of England, said that 'armies of footmen and horse' were seen fighting in the sky over London and other places in England about the year A.D. 230. Thunder, tempests, and hail accompanied them. Britton says that all 'appear to be imaginary.' The Thames was frozen over for five weeks in A.D. 230. Three years later, there was rain in Scotland for seven months, followed by a famine.

It rained blood in various parts of Britain, and 'a Terrible Bloody Sword' was seen in the sky after sunset for three nights when the emperor Decius came to the throne in A.D. 249. The Chinese astronomers recorded a great comet in every year from A.D. 252 to 254. One which appeared on March 24, A.D. 252, was a white 'broom star' which developed a tail 90 degrees long. Another broom star 75 degrees long appeared in December 253 and was visible for an almost incredible 190 days. In December of A.D. 254, a 'white vapour' in Sagittarius extended across the entire sky.

A.D. 250 (or 251, or 252) was the year of a severe winter in Britain which froze the Thames for nine weeks. In A.D. 291 most British rivers were frozen for six weeks, or as some say, nine weeks.

From A.D. 287 to 293, Britain was the private empire of the Roman co-emperor Carausius, until his chief minister Allectus assassinated him. In A.D. 296, the imperial heir Constantius invaded Britain. He slipped past the fleet of Allectus in a dense fog, and regained the island for Rome.

Marcus Aurelius Carus suffered a fate unique for a Roman emperor in July or August of A.D. 283. He was killed by lightning in his tent on the banks of the Tigris near Ctesiphon while on a military expedition in Persia. Some have suggested that the 'lightning' was in fact the hand of the imperial bodyguard Diocletian, but this is gossip, apparently accepted by later historians in the belief that Roman emperors were immune to lightning.

Halley's Comet rounded the Sun on April 7, A.D. 295, and was seen for seven weeks in China. It would return in A.D. 374.

Gaius Flavius Constantine was preparing to fight Maxentius, the last of various usurpers to the rule of the Roman Empire, just outside Rome on October 28, A.D. 312. Just after noon, Constantine saw, as Eusebius says, “with his own eyes, the trophy of a cross of light in the heavens above the Sun, and bearing the inscription 'Conquer by this' (in hoc vince). At this sight he himself was struck with amazement, and his whole army also, which...witnessed the miracle.”

The sight converted Constantine, who had previously worshipped Sol Invictus (the Unconquered Sun), to Christianity. His army, bearing the cross as their standard, drove Maxentius' forces back towards Rome. The Milvian Bridge collapsed under the weight of the usurper's fleeing troops, and Maxentius himself was drowned.

The original event has been, most historians believe, exaggerated by later writers for propaganda purposes. But could a cross in the sky, or something like it, have actually appeared? Constantine's army claimed to have seen it, but they were hardly impartial observers.

There could have been a cross of light in the sky. A combination of the appropriately shaped ice-crystals falling through the atmosphere miles above Constantine's head could produce the appearance of a pillar of light above and below the Sun and a band of light (the parhelic circle) stretching horizontally on each side of the Sun. This is not a 'prosaic' explanation. The effect is rare, and beautiful, and would be worthy of awe.